The invention relates to a heat accumulator block for regenerative heat exchangers with a plurality of heat exchanger plates which, for formation of flow channels, substantially extend parallel to one another.
Heat accumulator blocks of this kind are, in general, pie-shaped and together form a rotor which for one revolution passes through two zones. In the first zone, it is subjected to a hot medium which releases heat to the heat exchanger plates. In the second zone a cold medium flows therethrough to which the stored heat is released. The heat exchanger plates are comprised, in general, of steel and, for increasing their corrosion resistance, are lined with enamel.
Regenerative heat exchangers serve preferably to transfer heat from a hot gas flow to a cold gas flow. An important field is flue gas scrubbing, for example, in power plants and incinerators, whereby the flue gas is scrubbed in a flue gas desulfurization device. Before entering it, it is cooled whereby its heat is transferred onto the regenerative heat exchanger. Subsequently, reheating takes place by using the heat stored within the heat exchanger.
When cooling, the temperature, in general falls below the dew point of the condensible materials contained in the flue gas.
They will precipitate on the heat exchanger plates at the heat accumulator blocks and form deposits. Furthermore, the cold gas coming from the flue gas desulfurization device is, to a certain extent, loaded with liquid droplets and solid particles which will also deposit on the plates and which will worsen the deposit effect.
The channels in the heat accumulator blocks thus will become clogged to an increasing extent and thus require regular and rather frequent cleaning. This is done by exposure to a stream of air, water, or steam. For each cleaning process, a certain amount of freshly formed deposits will remain adhered to the plates so that the clogging of the channels is only delayed by the cleaning processes. As soon as the flow channels can no longer be reached by the cleaning processes, an exchange of the heat accumulator blocks must be performed.
It is an object of the invention to extend the service life of heat accumulator blocks.